x Abu Dhabi, UAEThursday 18 January 2018

Hefty Porsche Panamera S Hybrid defies logic, but to good effect

Road Test Somehow, Porsche has managed to get great emissions ratings out of this heavy Panamera.

It gets top marks for fuel consumption but not as much on price. Newspress
It gets top marks for fuel consumption but not as much on price. Newspress

I studied engineering at university. Laplace transforms and computational fluid dynamics may seem poor building blocks for perfect prose, be they automobile-related or otherwise, but I was eager to design the world's greatest car. Automobile magazines were just a nice diversion, not a career choice. My entire adolescence was geared to automotive mechanics. I was going to be the Canadian Enzo Ferrari.

And then they told me it would probably be 20 years before I was allowed to vector analyse anything more substantial than the rear bumper of a Ford Crown Victoria. So it was off to automotive journalism for an impatient young David Booth. All that gearhead training does mean, however, that I pride myself on being among the more technically astute of auto scribes. What I may lack in turn of phrase, I like to think I make up in deciphering camshaft phasing.

That's why it pains me to admit that I am not quite sure why Porsche's new Panamera Hybrid S gets such good mileage. The good news, of course, is the electrified Porsche does indeed get excellent fuel economy, especially for a car that weighs more than two tonnes and purports to be sporty. Bounding along the motorway at a slightly-more-than-illegal speed, the Hybrid S's little digital readout said we were averaging about 8.0L/100km. Even when I factored in a week's worth of slow-motion city driving, the Panamera only consumed 10.0L/100km, impressive stuff for a car roughly the size of a cruise ship.

But, as I said, the problem is that I don't quite understand how it does it. Porsche's version of hybridisation is of the parallel variety - there's an electric motor sandwiched between the engine and transmission. But, according to the car's display, the electric portion of the Hybrid's powertrain makes precious little contribution during normal driving. You can feel the electric engine kick in when you're pulling away and there's an extra kick at full throttle but, in most other circumstances, if that little histogram is to be believed, the electric motor doesn't seem very active.

All I can say is that this car achieved surprisingly good fuel economy under my normally profligate right foot. Even if I am not quite sure how Porsche's hybrid achieves its parsimony, one can't deny its success.

There are a few clues, however. One of the most noticeable aspects of the Porsche's operation is how often the petrol engine shuts down. Like most hybrids, the Panamera stops internally combusting at red lights, but the Porsche system takes it a step further, shutting down the engine as soon as you take your foot off the accelerator. The little screen that displays EV operation also has a readout that shows engine-off or "sailing" mode and you'd be surprised at how much time the car spends with its V6 completely inert.

As for the further contention that I've read from other motoring journalists that the hybrid's combination of electric motor and supercharged V6 effectively emulates the performance of Porsche's V8, I'm unconvinced. The electric motor's low-speed torque makes initial acceleration quite entertaining and Porsche claims it is but 0.6 seconds slower (6.0 seconds in all) than the V8 to 100kph, mighty impressive for something that weighs 1,984kg.

Full throttle passing, however, isn't quite as impressive. Porsche claims a total of 380 horses for the hybrid. With the petrol engine contributing 333 of those ponies, that means the electric motor adds 47 more when you mat the throttle deep enough. I didn't feel it. The hybrid is plenty powerful, it's amazingly frugal, but it doesn't feel as sporting as the Panamera V8. That it weighs some 184kg more than the V8 surely contributes to its (only) relative lethargy.

The major problem facing sales of the hybrid, however, is that its admittedly impressive fuel economy comes at a steep price. A base model Hybrid retails for Dh464,000 - Dh93,900 more than a base V6 (albeit with less power) and Dh20,700 more than the V8-powered S model. Even the Panamera GTS, with 430hp of V8 goodness and all-wheel-drive, is just less than Dh50,000 more than this hybrid.

Nonetheless, Porsche's hybrid system did exactly what it was supposed to do - deliver superior fuel economy. A fact not diminished by me not knowing how it did it.

Base price Dh464,000

Engine 3.0L supercharged V6 with electric motor

Gearbox Eight-speed automatic

Power 333hp @ 5,500rpm

Torque 300Nm @ 3,000rpm - 5,250rpm

Fuel economy, combined 7.1L/100km